The invention relates to a shock wave tube of the type used for example to shatter kidney stones in a patient.
Shock wave tubes of this type are known. German Offenlegungsschrift 33 12 014 describes such a shock wave tube. Because of the strong (e.g. 100 bar) pressure pulses delivered, the materials of such a shock wave tube are heavily stressed as a result of successive discharges and shock wave emissions. In particular, the discharge coil (which is designed as a disk coil) and the membrane are subject to early material fatigue. In DE-OS 33 12 014 the metal membrane is circumferentially symmetrical and is provided with differing effective cross-sections in order to increase its lifespan. In addition it is indicated that service life is prolonged if pressure is employed to hold the diaphragm against the disc coil.
A shock-wave tube of the type considered herein is also described in commonly owned patent application Ser. No. 634,021, filed 07/24/1984 and entitled "Apparatus for the Contact-Free Disintegration of Calculi", the disclosure of which application is incorporated herein by reference.
One object of the invention is to provide a shock wave tube that will survive many shock wave emissions.
Another object is, in general, to improve on the prior art.